#level {
  font-size: 1.25em;
  margin: 10px;
  width: 100px;
  grid-column: 1/6;
}

#board {
  display: grid;
  grid-template-columns: 80px 80px 80px 80px 80px;
  grid-gap: 10px;

  .tile {
    border: 1px solid black;
    border-radius: 16px;
    width: 80px;
    height: 80px;
    cursor: pointer;
    position: relative;
    perspective: 1000px;
    transform-style: preserve-3d;
    transition: rotate 500ms linear;

    .blue,
    .yellow {
      border-radius: 16px;
      position: absolute;
      backface-visibility: hidden;
      width: 100%;
      height: 100%;
    }

    .blue {
      background-color: blue;
    }

    .yellow {
      background-color: yellow;
      rotate: y 180deg;
    }
  }

  .on {
    rotate: y 180deg;
  }
}

#reset {
  margin-top: 10px;
  grid-column: 1/6;
}